This invention relates to ultrasonic devices and more particularly to an ophthalmic phacoemulsification handpiece.
A typical ultrasonic surgical device suitable for ophthalmic procedures consists of an ultrasonically driven handpiece, an attached hollow cutting tip, an irrigating sleeve and an electronic control console. The handpiece assembly is attached to the control console by an electric cable and flexible tubings. Through the electric cable, the console varies the power level transmitted by the handpiece to the attached cutting tip and the flexible tubings supply irrigation fluid to and draw aspiration fluid from the eye through the handpiece assembly.
The operative part of the handpiece is a centrally located, hollow resonating bar or horn directly attached to a set of piezoelectric crystals. The crystals supply the required ultrasonic vibration needed to drive both the horn and the attached cutting tip during phacoemulsification and are controlled by the console. The crystal/horn assembly is suspended within the hollow body or shell of the handpiece at its nodal points by relatively inflexible mountings. The handpiece body terminates in a reduced diameter portion or nosecone at the body""s distal end. The nosecone is externally threaded to accept the irrigation sleeve. Likewise, the horn bore is internally threaded at its distal end to receive the external threads of the cutting tip. The irrigation sleeve also has an internally threaded bore that is screwed onto the external threads of the nosecone. The cutting tip is adjusted so that the tip projects only a predetermined amount past the open end of the irrigating sleeve.
When used to perform phacoemulsification, the ends of the cutting tip and irrigating sleeve are inserted into a small incision of predetermined width in the cornea, sclera, or other location in the eye tissue in order to gain access to the anterior chamber of the eye. The cutting tip is ultrasonically vibrated along its longitudinal axis within the irrigating sleeve by the crystal-driven ultrasonic horn, thereby emulsifying upon contact the selected tissue in situ. The hollow bore of the cutting tip communicates with the bore in the horn that in turn communicates with the aspiration line from the handpiece to the console. A reduced pressure or vacuum source in the console draws or aspirates the emulsified tissue from the eye through the open end of the cutting tip, the bore of the cutting tip, the horn bore, and the aspiration line and into a collection device. The aspiration of emulsified tissue is aided by a saline flushing solution or irrigant that is injected into the surgical site through the small annular gap between the inside surface of the irrigating sleeve and the outside surface of the cutting tip.
Ultrasound handpieces are subjected to the extreme heat and pressure of autoclave sterilization, which can shorten the life of the piezoelectric elements. Prior attempts to increase the longevity of the electronic components of piezoelectric handpieces have been directed primarily to preventing moisture from entering the handpiece by better sealing of the outer shell and/or electric cabling. While these attempts have increased significantly the useful life of ultrasound handpieces, further improvements are needed.
Accordingly, a need continues to exist for an ultrasound handpiece having increased reliability.
The present invention improves upon prior art ultrasonic devices by providing a handpiece having a set of longitudinally vibrating piezoelectric elements and which may additionally have an electric motor to provide rotational or oscillatory movement to the ultrasound horn. The piezoelectric elements are surrounded by a high temperature plastic sleeve, and the sleeve is filled with high temperature potting material. The potting material seal the piezoelectric elements against moisture without affecting the performance of the piezoelectric elements.
It is accordingly an object of the present invention to provide an ultrasound handpiece having both longitudinal and torsional motion.
It is a further object of the present invention to provide an ultrasound handpiece having piezoelectric elements sealed against moisture.
Another objective of the present invention is to provide a more reliable ultrasound handpiece.
Other objects, features and advantages of the present invention will become apparent with reference to the drawings, and the following description of the drawings and claims.